Sophorolipids are biosurfactants produced by several yeast species. In Candida bombicola, the hydrophilic moiety of the biosurfactant molecule is a disaccharide (i.e., sophorose), and the hydrophobic portion is an omega- or (omega-1)-hydroxy fatty acid attached to the sophorose via a glycosidic bond. The fatty acid chain, most commonly containing 16- and 18-carbon atoms, may be unsaturated and lactonized to the disaccharide. The disclosed potential applications of Sophorolipids include serving as environmentally friendly surfactants in oil recovery, and as active ingredient in detergent, cosmetic and lubricant formulations. Sophorolipids are also known to have antimicrobial activity. Sophorolipids produced by Torulopsis sp. consist of a dimeric sugar (sophorose) and a hydroxyl fatty acid linked by a B-glycosidic bond.
There are generally considered to be two types of sophorolipids, the acidic (non-lactonic) and the lactonic sophorolipids. The hydroxyl fatty acid moiety of the acidic Sophorolipids forms a macrocyclic lactone ring with the 4″-hydroxyl group of the sophorose by intramolecular esterification. Lactonic Sophorolipids have attracted more attention then their acidic counterparts. The acetylated lactonic Sophorolipids have been applied in cosmetics as antidandruff, bacteriostatic agents and deodorants.
Sophorolipids may be obtained from Candida apicola, Candida bombicola ATCC 22214 , Candida lipolytica and Candida bogoriensis when grown on carbohydrates, hydrocarbons, vegetable oils or their mixtures. They are produced as a mixture of six to eight different hydrophobic sophorosides.
EP 499 434 (Unilever) discloses the improved oily soil detergency of mixtures of a sophorolipid (SOL-TUBS a sophoroselipid from technical University of Braunchweig, Germany); produced by torulosis bombicola. It comprised a mixture of four different sophorolipids, the main fatty acid chain length being C18. Examples 5, 6 and 7 of this patent application use blends of sophorolipids with specified nonionic surfactants. The nonionic cosurfactants used were: Synperonic A3 (an alcohol ethoxylate containing a certain amount of branching in the hydrophobe and manufactured from petrochemical fatty alcohol by reaction with 3 moles of ethylene oxide), a C12 1,2-diol and a C10 monoglycerolether. The application also suggests that the biosurfactants can be used with anionic surfactant: dialkyl sulphosuccinates are said to be of especial interest on page 7. There is no mention of mildness or foaming.
U.S. Pat. No. 5,417,879 (Unilever) also discloses combinations of glycolipid and non-glycolipid surfactants for oily/fatty soil detergency. Sophorolipids are mentioned among the glycolipids and dialkylsulphosuccinates are mentioned among the preferred non-glycolipid surfactants. However, all of the examples with sophorolipids use nonionic cosurfactants.
U.S. Pat. No. 5,520,839 (Unilever) makes a similar general disclosure and synergistic detergency claim, but also describes specific examples of dialkyl sulphosuccinates to include those in which both alkyl substituents contain at least 4 carbon atoms, and together contain 12 to 20 carbon atoms in total; such as di-C8 alkyl sulphosuccinate. This surfactant was exemplified with rhamnolipid, but the sophorolipids were only exemplified in combination with nonionic surfactants.
DE 19600743 (Henkel) discloses combinations of sophorolipids and anionic surfactants. No disclosure of combinations with dialkoxy sulphosuccinates or alkyl glycinate is made.
EP 1 445 302 (Ecover) discloses a detergent composition comprising at least one glycolipid biosurfactant and at least one non-glycolipid surfactant. In several examples, a Sophorolipid (Sopholiance from methyl ester of rapeseed oil ex Soliance) was used. Foam quality when used in combination with various nonionic surfactants and also anionic surfactant (SLS) was investigated.
EP 1 953 237 (Ecover) discloses a method for producing short chain sophorolipids. It says that sophorolipids are one of the most promising biosurfactants, due to their high production yields and ease of recovery. It also says that they are mild to the skin.
WO 98/16192 (Alterna Inc) discloses a germicidal composition suitable for cleaning fruits, vegetables, skin and hair. The composition may comprise a mixture of anionic surfactant and sophorolipids biosurfactant. The anionic surfactants mentioned are those with biocidal activity: Sodium lauryl sulphate (SLS), Sodium lauryl ethoxy sulphate (SLES).
EP 550 276 (Unilever) describes a personal care composition comprising a mild and foaming glycolipid used with a co surfactant (e.g. SLS). The glycolipid is a uronic acid derivative. No synergy is observed for either mildness or foam between the biosurfactant and the SLS or SDS.
WO 96/12469 (Unilever) describes a personal care composition comprising a lipid, which may be a glycolipid such as a glycosyl glyceride of diacyl or dialkyl saccarides (eg a sugar ester), a surfactant and a deposition aid. Preferred mild surfactants include alkyl ether sulphate, alkyl glyceryl ether sulphate, sulphosuccinates, taurates, sarcosinates, sulphoacetates, alkyl phosphate, alkyl phosphate esters, acyl lactylate, and alkyl glutamates. Examples used SLES or APG with the sugar ester lipid.
DE 196 48 439 & DE 196 00 743 (Henkel) describe the use of a mixture of glycolipids, which specifically includes sophorolipids and a long list of possible anionic surfactants, including mono and dialkyl sulphosuccinates. In the only example for each document that uses sophorolipid, it is combined with SLS as anionic surfactant.
FR 2 792 193 (Lavipharm Lab) describes a cosmetic base comprising a composition rich in lipids of vegetable origin and at least one surfactant. A shampoo composition is disclosed with the lipids used in approx 1:1 ratio with a surfactant, which is itself a mixture of anionic and amphoteric surfactants. The anionic component is an alkyl sulphate.
U.S. Pat. No. 5,654,192 (Institut Francais du Petrole) discloses compositions containing an anionic and/or nonionic surfactant, and at least one glycolipid. The composition is used for decontaminating a polluted porous medium. Sulphosuccinates and sophorolipids are both mentioned. There are specific examples using combinations of sodium dioctyl sulphosuccinate and sophorolipids showing the synergistic effect on lowering of interfacial tension. Neither foaming, nor mildness to human skin is mentioned. No aqueous concentrated composition is disclosed. In use, the materials are mixed with water but there is then less than 1% of the sophorolipids.
JP 2006070231 A (Saraya), discloses a biodegradable liquid cleaning composition e.g. liquid body cleaning composition for jet washing. The composition contains sophorolipids comprising 90% or more acid-type sophorolipids. The compositions are used as a liquid body cleaning composition for jet washing. The biodegradable liquid cleaning composition has excellent cleaning power and low foaming property. The acid-type sophorolipid is chemically stable in the liquid cleaning composition.
KR 2004033376 A (LG Household & Healthcare Ltd) describes a cosmetics composition comprising sophorolipids. The cosmetics composition comprises, as an active ingredient, sophorolipids, which are produced from Candida bombiocola (ATCC 22214). The cosmetic composition has excellent sterilization effect as well as moisturising and softening effects on the skin. A cosmetics composition is characterized by comprising, as a biosurfactant, 0.01-10 weight % of sophorolipids. The composition is formulated into face lotion, nutritive emulsion, face cream and the like.
WO 9534282 (INST FRANCAIS DU PETROLE) discloses cosmetic and dermatological compositions containing sophorolipid (s) —as radical scavengers, elastase inhibitors and antiinflammatory agents.
There is an unmet need for a mild and high foaming surfactant system for use in personal care (cleaning) products that employs surfactant systems that can be considered relatively environmentally friendly.